The invention relates to a fuel supply system for a mixture-compressing, spark-ignited four cycle internal combustion engine with charge stratification wherein the largest part of the charge is introduced into a main combustion chamber as a lean fuel-air mixture through at least one inlet valve by a main mixture-forming system, for example, a carburetor, and the fuel of the residual portion of the charge, constituted by a fuel-enriched fuel-air mixture, is introduced directly into an auxiliary combustion chamber joined to the main combustion chamber by way of a firing channel with the aid of an auxiliary combustion chamber injection pump by way of an injection nozzle; and wherein the fuel supply system comprises a fuel tank.
In a conventional fuel supply system for a mixture-compressing, spark-ignited four cycle internal combustion engine with charge stratification of the above-mentioned type, a fuel feed pump is provided for the fuel of the lean fuel-air mixture fed to the main combustion chamber via a carburetor, and a fuel feed pump is provided for the fuel of the rich fuel-air mixture fed via an injection pump into the auxiliary combustion chamber. These two fuel feed pumps are necessary, because the injection pump requires a fuel feed pressure of about 1 bar, and the carburetor requires merely a fuel feed pressure of about 0.2 bar. The expenses involved in manufacturing such a fuel supply system are relatively high due to the necessity of providing two fuel pumps.
It is an object of the invention to provide a fuel supply system for an internal combustion engine of the type mentioned hereinabove, which involves less expenses than required for the conventional fuel supply system.
According to the invention, this object is attained by a preferred embodiment in that the fuel supply system has a single fuel feed pump, by means of which the fuel is conveyed from the fuel tank directly to the auxiliary combustion chamber injection pump and to the carburetor via a pressure reducing valve. Thereby, a fuel supply system has been created for internal combustion engines with charge stratification which exhibits, in addition to the lower capital outlay, also a higher functional safety than the conventional fuel supply system since a pressure reducing valve, due to the fact that its structure is simple and its operation reliable, has a lower susceptibility to disturbances than an electric fuel feed pump.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, a single embodiment in accordance with the present invention.